>How's that antenna doing? The last few Galileo updates that I've seen
>posted here had nothing to say on the subject. Did they fix it or
>give up on it? Is there hope?
The High Gain Antenna is still not functional. Someone from JPL told me
recently that they have discovered that if they turn on the motor very briefly,
it will advance a tiny amount, but not slip back. He said that they plan to
try this up to a hundred times and hopefully will be able to get the screw to
advance at least a full revolution. He was optimistic, but "we won't know until
we try."
It should be noted that thanks to compression techniques, JPL expects to do
75% of the science they had planned even if the HGA never opens, including
receiving 100% of the data from the atmospheric probe.
--
Josh Hopkins Friends don't let friends derive drunk
j-hopkins@uiuc.edu
------------------------------
Date: Sat, 29 Aug 1992 16:29:20 GMT
From: GRASSO CHRISTOPHER A <grasso@tramp.Colorado.EDU>
Subject: LDO shuttle and pilot readiness
Newsgroups: sci.space
After being on orbit for 2 months, how realistic is it for a shuttle pilot
to be capable of performing a reentry and landing? Seating in the
shuttle is upright, airliner-style, while seating in a capsule is
reclined to horizontal.
If the extended stay in microgravity damages the shuttle pilots'
ability to bring the spacecraft back for a landing, doesn't this
mandate a separate ACRV if shuttle is to be used for resupply and
crew rotation?
-Chris
--
Chris Grasso
CSC
Univ. of Colorado, Boulder
------------------------------
Date: Sat, 29 Aug 1992 10:11:35 GMT
From: Paul Dietz <dietz@cs.rochester.edu>
Subject: Magnetic Sail
Newsgroups: sci.space
In article <QebfaQK00awS0AiVIq@andrew.cmu.edu> ep1a+@andrew.cmu.edu (Eric Eimal Paulsen) writes:
> Maybe you've already heard of this, but I just read an article in the
> May or July '92 Asimov Sci-Fi magazine about a magnetic sail idea. It
> started from a ram scoop and was turned into a superconduction loop held
> from the center by lines. It works on the premise of skipping around in
> LEO by working against the Earths magnetic field until it gets into the
> solar wind and can deflect it, gaining something like .02 g, much better
> than Ion Drive. Really good for interplanetary travel. Possible
> application as brake in interstellar flight, eliminating half of fuel
> load. The article (about ten pages long) has a lot of mathmatics to back
> it up, way over my head. Fascinating implications!
Unfortunately, I get the impression they badly miscalculated the
tension on the loop, which renders the whole idea much less interesting,
as the loop would have to be much more massive.
(It was Analog, not IASFM.)
Paul F. Dietz
dietz@cs.rochester.edu
Great moments in humanitarianism:
"How can we help a foreign country to escape overpopulation?
Clearly the worst thing we can do is send food . . . .
Atomic bombs would be kinder. For a few moments the misery
would be acute, but it would soon come to an end for most of
the people, leaving a few survivors to suffer thereafter."
Garrett Hardin, 1969.
------------------------------
Date: 29 Aug 1992 16:46:13 GMT
From: Frank Crary <fcrary@ocf.berkeley.edu>
Subject: Magnetic Sail
Newsgroups: sci.space
In article <1992Aug29.101135.16007@cs.rochester.edu> dietz@cs.rochester.edu (Paul Dietz) writes:
>Unfortunately, I get the impression they badly miscalculated the
>tension on the loop, which renders the whole idea much less interesting,
>as the loop would have to be much more massive.
Actually, he didn't calculate the loop tension at all. (At least
not in the pre-print of the technical paper I have.
He caluclated a mass based on the critical current density and mass
density of the superconductor, and the loop current:
M = 2pi*RAp = 2pi*RIp/J
Where R is the sail radius, A is the cross sectional area of the loop,
p is the mass density of the material, I is the maximum loop current
and J is the critial current density of the superconductor.
Zubrin seems to simply assume the tension on the loop will be low.
A more serious problem is his use of high temperaature superconductors:
He assumes nitrogen-temereature superconductors with properties like
those of helium-temereature ones. We don't have anything like that at
the moment, and the people working in the field have been promising
them "soon" since high temperature superconductors were first dicsovered
6 years ago.
Frank Crary
CU Boulder
(By the way, does anyone know how to get a usenet feed here at
Boulder? My new account is on pprince, which doesn't seem to accept
news commands. Remote logins to my old Berkeley account are getting to
be a pain...)
------------------------------
Date: 30 Aug 92 06:13:00 GMT
From: Dave Beaujean <Dave.Beaujean@davespc.mi.org>
Subject: Mars Pictures request
Newsgroups: sci.space
Hi All!
I am looking for picture of Mars which would let me become
familiar with Mars before the mapping project gets going.
I am especially interested in the "Face on Mars" area which
I have only heard mentioned before. I know there are
bazillions of gifs on ames and spacelink, but I was wondering
if there is a specific area where these type of pictures may
be located at. Any help would really be appreciated!!!
Dave (New father of a future space traveler!!!)
------------------------------
Date: 28 Aug 92 17:30:02 GMT
From: Steve Ispas <sispas@lsil.com>
Subject: Size,Mass,and velocity....
Newsgroups: sci.space
I think Tom Nugent is right when he writes:
Flame on!}
I don't mean to flame, but this seems to be a big waste of bandwidth. You
can find things like this just about anywhere. Surely in an encyclopedia,
if not a good dictionary. Call up your local library (you don't even have
to leave home) and they may be willing to give it to you over the phone.
Otherwise, go to the library, and look it up along with ten zillion other
neat things about space you can find there.
{Flame off!}
The idea is not that he is a spoilsport. The idea is that he is helping by pointing out the library, which is an excellent source of information rather than putting it on the network. It's not a matter of wasting bandwidth, but if someone is interested in that kind of statistical information he/she would find so much in a library, or encyclopedia.
